The present invention relates to a method and apparatus for forging helical or spirally toothed gear members, particularly bevel gears having arcuately generated teeth. The present invention is also applicable to the production of spur gears as well as bevel gears having teeth shapes made, for example, in accordance with the Gleason, Oerlikon, or Klingenberg process systems.
A process for forging straight-toothed bevel gears is known from the German patent pre-publication DT-AS No. 2,144,006. Another process wherein planar gear wheels having spiral teeth are forged or sintered from powdered materials is described in German patent pre-publication DT-AS No. 2,002,684. In this latter publication, a press-mold is employed having a movable ram die which passes through the mold, as an ejector for the ready-forged gear blank. Here, the press-die is provided with a tooth configuration which engages in a corresponding set of teeth formed in the mold. The press-die is rotated during its stroke movement in accordance with the spiral configuration of the engaging toothing. In this device, which serves a purpose different from that of the present application, the lower die has a specific purpose and is adapted only for the formation of specific gear blanks. The lower gear die itself is movable and assumes also the functions of an ejector. As a result, the suitability of the device described in the aforementioned publication is limited to the formation of cylindrical gear wheels with spiral gear faces. Heretofore, the forging of bevel gears has been impossible or limited only to planar gear wheels having hardly noticeable curvature of the teeth, since it is only in these cases in which ejection of the die is possible within the limitation set by the taper of the gear blank. On the other hand, bevel gears having a more marked setting, i.e., with a less steep central pitch of their teeth, could not be forged in a press die, due to the impossibility of removing the finished forged blank from the die.
It is an object of the present invention to provide a method and apparatus for simplifying the forging process of bevelled gears having helical or spiral toothed faces, enabling the large scale production of such gears, at least for those forms of gears having teeth with a fairly constant pitch.
It is a further object of the present invention to provide a method and apparatus for forming helical and spiral tooth gears which overcomes the disadvantages and defects of the prior art and which enables the production of a wide range of spiral or helical bevels.
It is a further object of the present invention to provide simple forging apparatus for the formation of bevelled gears.
The foregoing objects, other objects, and numerous advantages of the present invention are set forth in the following disclosure and will be clearly obvious therefrom.